This invention relates to an encrypted data communication system for communicating the encrypted data, or in particular to a technique for suppressing the effect of erroneously detecting a dummy code contained in the encrypted data as a location identification code (such as a start code).
In recent years, a method has spread widely in which the video data is encoded (and compressed) digitally to generate a video stream which is distributed to terminal units (clients) from a server.
As a method of distributing video data only to limited terminal units, the method of encrypting the non-header part of the video stream has been conceived. In this method, correct video data reproduction is possible by the terminal units having a cryptographic key. The terminal units having no cryptographic key, however, can obtain only the video data of a deteriorated image quality.
The applicants considers that the above described conventional technique is already known prior art. The present applicants, however, could not find the appropriate document as of the time of filing the basic Japanese application, and therefore the document information of the prior art are not described.